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Nitrous Experts...

Discussion in 'The Garage' started by OffRoader93, Mar 11, 2005.

  1. OffRoader93

    OffRoader93 1/2 ton status

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    How big of shot of nitrous would be safe to give to a big block chevy with all stock lower end? Thanks.

    Brenton
     
  2. camarossguy2

    camarossguy2 1/2 ton status

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    big block...i dunno, but the safe limit for LT1s and LS1s is commonly 100 dry or wet and 150 wet is the is pushing the safe detartment.

    I assume non of your bigblock is running forged internals, that mixed with the assumption your using this in a 4x4 (lower rpm range while spraying) I will think a 100 shot would be more then enough and your safe limit. Although improper use, you can blow it up with only a 50 lol
     
  3. Ryan B.

    Ryan B. 3/4 ton status GMOTM Winner

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    safe huh?
    well i'd include all the safety features to make it safe. RPM window switch, fuel pressure safety switch, WOT switch, maybe 2 solenoids for the nitrous line so it can't stick open...
    I've seen in Chevy High Performance magazine, they took a junkyard 350, threw a nitrous cam in it... it survived 100, 200, and a 300 shot making around 600hp on the engine until they blew it up by purging the nitrous into the engine at idle. DOH!
    Factory stock v-8 engines handle about 100-150 without too much modification. My buddy just blew up a piston in his 383 on the dyno by butting the ring ends of the top ring.. This was Before he even added nitrous on his engine, if the rings were about to butt ends just on the motor i'd say he would have been in big trouble if he added some juice.

    I'd want forged pistons for 100 shot or bigger.
    I just pulled apart my camaro's BBC and gapped the rings bigger to ensure that i won't be butting ring ends if i decide to go with a 150-250 shot.
    Stock engines call for around .003" x bore
    Race nitrous applications call for about .006" x bore.
    I gapped my rings like .026/.024" instead of like .018/.016"
    You'll want to pull back 2* of timing per 50HP of nitrous, and over 125-150 hp go with one step colder plug. Race fuel is a good idea if over 100 shot.
    I'm thinking of going with a seperate 1 gallon fuel cell with 118 octane and dedicated fuel pump and regulator just for the nitrous enrichment.
     
  4. boz42

    boz42 1/2 ton status GMOTM Winner

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    call for what? is that a ring gap guide or what? could u explain a little more

    .003 X 4.25(bore) = .01275?

    thanks
     
  5. camarossguy2

    camarossguy2 1/2 ton status

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    I think he is refering to the piston to bore clearance.

    for example...if the piston is 4.030 and the bore is 4.030, good luck getting the piston in the hole.
    A proper machinst with measure the pistons and the bore between .002-.007 ish depending on the application. N/a is about .004...biiger for nitrous is for heat expansion. but realize with bigger gap = piston slap when cold.
     
  6. RustBuket

    RustBuket 1/2 ton status

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    That means that if you have a stock engine, you should have a gap of .01275 " between the ends of the rings when installed in the cylinder. (12.75 thousandths)
     
  7. Ryan B.

    Ryan B. 3/4 ton status GMOTM Winner

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    Yes.
    I mentioned RING GAP a couple of times, i wasn't clear?
    Ring gap will be different between a forged and hyperutectic (fancy name for cast) piston.

    Speed Pro recommendations:
    *Top Ring*
    Moderate Performance: .004 x bore diameter
    Drag Racing & Oval track: .0045 x bore diameter
    Nitrous Street: .006 x bore
    Nitrous Drag: .008 x bore
    Supercharged: .006 x bore

    *2nd ring*
    Moderate Perf: .003 x bore
    Drag & Oval track: .0035 x bore
    Nitrous Street: .005 x bore
    Nitrous Drag: .0065 x bore
    Supercharged: .005 x bore


    My bore is (4.25+.070 over) = 4.320
    Drag racing= 4.320 X .0045 and .0035 = .01944 and .01512
    Nitrous Street = 4.320 X .006 and .0055 = .02592 and .02376

    which is about where i gapped my rings for some nitrous .026 and .024 instead of .018 and .016 ish.
     
  8. boz42

    boz42 1/2 ton status GMOTM Winner

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    i figured u meant that, but it wasn't clear to me. thanks for clarifing
     

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